Differential Diagnosis

Points to remember and for easy recall

• brief psychotic, schizophreniform and schizophrenia differs in its timeline. BP- upto 1 month, schizophreniform is 1 month to 6 months and schizophrenia is over 6 months.
• distinguishing schizophrenia from schizo affective is by considering  duration as well as mood symptoms. 
• Major Depressive disorder vs depressive disorder NOS vs Dysthymia : MDD and DD NOS is distinguished with severity of symptoms. MDD impaires biological functioning. D NOS is not that severe yet. Dysthymia is when person has low level of depression for 2 years (adults : 2 yr, children and adolescents : 1 yr)
• Bipolar I and Bipolar II and Cyclothymia : bipolar i needs a manic phase at least 7 days. some depression may follow it. Bipolar II needs 2 things. hypomanic phase and manic depression. hypo-mania is symptoms present atleast 4 days.cyclothymia is a milder than both with mild depression and mild manic phase, not as much as bipolar II
• Schizo affective vs mood disorder with psychotic features: both of these has a psychotic element and mood element. the difference is whatever the dominant symptom. in former the dominant feature is psychotic symptom or psychosis and having additional mood features coming in and out. the same goes with mood disorder.  
• bereavement vs major depressive disorder vs adjustment disorder with depressive mood:                    the primary difference between Bereavement and MDD is timeline. 2 months or less, bereavement and more MDD. Adjustment disorder is least pathological diagnosis always has the feature of change or recent stressor which cannot be the death of somebody, if someone dies its clearly bereavement, while adjustment is about change in which symptoms need to start within three months after stressor and not longer than 6 months with changes like job change marriage, school change.
• Panic disorder without agoraphobia vs PD with agoraphobia : in former the client does not associate the panic attack with situation hence there is no fear and worry about having an additional attack, whereas in PD with agoraphobia, the client associates the panic attack with the situation and worries about having another attack and therefore changes is behavior to avoid situations. excess fear and worry.
• OCD and OCPD (personality disorder : the former is where the person has obsessions and compulsions. a recurring thought or ideas, having hard time controlling the thought, and a compulsion is an action which is done in response to obsession. the later is about the personality being perfection and control. OCPD is- perfectionist. who likes to delegate actions, wants to control. there's no impairment in functioning as in OCD.
• PTSD vs acute stress disorder vs adjustment with anxious mood: PTSD and ASD a person has to be exposed to a trauma. the difference is timeline, the former needs to be present atleast a month and for ASD its less than a month. adjustment disorder with anxious mood does not have severe symptoms ans PTSD and ASD.

• GAD vs GAD NOS vs adjustment disorder with anxious mood : timeline and severity
• dementia vs delirium : dementia common with elderly, dementia is an irreversible state while delirium is  a state that is going to pass. dementia is about cognitive decline and memory loss with gradual onset. it has its own types. while delirium is a transient state that accompanies illness, side effect of drug with rapid onset in change in consciousness, with agitation and personality change. 

• Somatzisation disorder vs conversion vs hypochondriasis - all of these has to do with physical body. the first one is about cluster of symptoms associated with pain  with or without good medical explanation. conversion disorder is when the physical symptoms brought on by psychological disorder eg: blind rage. a psychological experience gets converted to physical manifestation. with hypochondriasis, is constant worry about getting sick. 

• factitious disorder vs malingering vs munchousen syndrome by proxy : a conditions by which a person acts ill , take something to make them sick to assume sick, while malingering is also sick, but drama made to get gain, not about producing symptom but getting sick pretending to be sick, the last one is the care giver likes being care giver for the sick person, making the person deliberately sick
• Anorexia vs bulimia: must involve a doctor, for anorexia, the person has to 85% or less their normal body weight, no periods, not just skinny but overwhelming fear of gaining weight. two types, restricting type and purging type where theres binge eating and throwing up anorexia. bulimia's defining feature is binge eating. eat large amount of food in 2 hr period which has a sense of lack of control, even bulimia has purging type and non purging (fasting, exercise)type.
• eating disorder NOS and body dysmorphic disorder  : clinicially significant distress on subjective dislike of a body part
• depersonalization disorder vs dissociative amnesia : in former the person feels outside of body, very detatched from body, like in dream. can be caused by drug. with dissociative amnesia, there's an episode in which there's inability recalling particular event/episode
• dissociative fuge vs dissociative identity disorder : when theres one or more episode of amnesia where the person loses sense of identity or past where the person travels away from home and cannot give any information about themselves. DID is the presence of two or more distinct identity or personalty states. each identity has their own memory and thinking, and they can alternate between taking over in each time.
• sexual aversion disorder vs dysparuenia vs vaginismus : sexual aversion disorder is when a person has disgust feel towards genital contact, repulsed by it. dyspaerunea is associated with pain in sexual intercourse with no physical medical explanation, vainusmus is recurrent involuntary spasm in outer wall in vagina that interferes in natural sexual intercourse and pain in sex.
• primary insomnia vs primary hypersomnia : the former is difficulty initiating and maintaining sleep for 1 month, this causes disturbance in functioning, and the later is about over sleeping. 
• nightmare disorder vs sleep terror disorder : the former reports a nightmare and in sleep terror is about waking screaming with no memory of nightmare 
• intermittent explosive disorder vs kleptomania vs trichtillomania : former is about anger outburst, kleptomania about stealing, and trichotillomania is recurrent pulling of hair .
• substance abuse vs substance dependence vs poly-substance abuse : SA when drinking or substance use causes problem like DUI, SD is when the person gets so used to the substance where the person has withdrawal or tolerance. so people use  more substance to achieve desired effect and has effects when trying to stop using the substance. poly SA is when the person is using/abusing atleast 3 substances
• substance induced psychosis vs Substance induced mood disorder : the major difference is the type of substance used. 
• ego dystonic and ego syntonic : the former refers to the disorders where people don't like that they are experiencing their symptoms. (d- dont like symptom), ego syntonic is where the disorders are not seen problematic. this is seen in the personality disorders. ego syntonic- behavior is not seen as problem
• Paranoid Personality Disorder vs Delusional disorder Vs Paranoid Schizophrenia - with PDD, the person is highly suspicious with other people which is different in DD, where the person has non bizarre delusion (eromatic type, grandiose type, jealous type,persecutory type). PDD is pervasive. PSD that indicates that the person has had hallucinations.
• schizoid vs avoidant PD vs Major Depression- A schizoid is a loner, like to be alone, prefer to be alone and avoid social activities, limited social contact and feel ok to be alone, APD are lonely and shy but in need of social contact. with Major dep is ego dystonic, not as SPD or APD is ego syntonic.
• schizo typal PD vs schizophrenia- Schizotypal PD is like schizophrenia but no hallucination or bizarre delusion, but odd behavior, which makes it difficult to maintain relationships.
• Anti social Disorder vd Narcissistic - the precursor of the former is conduct disorder, issues with breaking the law and conformity to respect laws. reckless disregard for others safety and lack of remorse. narcissistic PD is about self importance and grandiosity. criticism makes them mad and expect favorable or best treatment and lack empathy. Narcissism is related to domestic violence, rage.
• borderline PD vs Histrionic - the former is very important cuz of the multiple suicidal gestures and unstable emotion leading to unstable relationship-seeing things in extreme, underlying feelings of abandonment, impulsive. issues of boundaries are very important in test. while histrionic is about dramatic and want to be center of attraction. dressing seductively and constantly seek approval.
• Dependent PD vs OCPD- dependency and inability to make own decisions, fear of being alone and abandoned. unlike borderline they are very attached to the person/relationship. OCPD is when a person is perfectionist, who comes under ego syntonic, think its fine way to be. they are obsessed with rules, procedures, lack of flexibility etc

Reference :

DSM IV TR